[Export(typeof(IShell))]
    public class MainWindowViewModel : Conductor<object>.Collection.OneActive, IShell, IHandle<IShell>
    {
        readonly IWindowManager _windowManager;
        public Setting set { get; set; }
        public IShell Shell;

        [ImportingConstructor]
        public MainWindowViewModel(IWindowManager windowManager)
        {
            set = new Setting();
            Shell = this;
            this._windowManager = windowManager;
        }